GOING INTO BLAST WITH 



BY T. EGLESTON, Ph.D. 






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Reprinted from Schooe of Mikes 'Quartefey, May, 


6 


GOING INTO BLAST WITH ANTHRACITE 

FURNACES. 

BY T. EGLESTON, Ph.D. 

f 

The method of blowing in which is adopted in almost all 
the anthracite furnaces in the United States was imported orig¬ 
inally from Staffordshire, and has been modified to suit the cir¬ 
cumstances and conditions which arise from different situations, 
different fuels, different ores, and different shapes of furnaces. 
It is applicable to all kinds of fuel and is much safer and quicker 
than the method of scaffolding formerly used exclusively in 
charcoal furnaces, and still used in some of the European coke 
furnaces. With moderate care and precaution it has been so 
universally successful that a description of it cannot fail to be 
interesting. 

When a furnace has been lined new, the first thing to be 
done is to place a good roof over the top so as to prevent the 
action of the weather. Then all the lower part of the furnace 
being open the air is sometimes allowed to circulate through it 
for several weeks in order to air dry it as much as possible. In 
n >St works in this country, however, no air drying is done. It 
is considered either that the furnace has been so long in repair 
that the masonry is dry enough, or, if business is good that they 
cannot afford to wait, so that the fire is started as soon as the ma¬ 
sons have finished their work. When the furnace is ready, in open 
breast furnaces, a coal fire is made in the fore hearth which is 
transformed into a fireplace by building a temporary wall under 
the tymp and leaving a flue of about io inches square going 
directly into the furnace. The fore hearth is then arched over 
and a grate placed in it. The grate bars of the furnace will be 
about three feet long and the grate about 34 inches wide. As 
but little draft is required at first, the area of the flue is usually 
diminished by putting bricks into it. When the furnace has a 
closed breast, a temporary brick furnace 2 feet wide and 3 to 4 


IS'27 is? 


2 


feet long is built outside of the furnace and the heat carried in 
by a flue built for the purpose. As soon as this is ready the 
top of the furnace is covered loosely with sheet iron supported 
on iron bars in order to prevent the too rapid escape of hot air. 

A fire is then lit in the furnace which is kept up until there 
is no condensation of moisture anywhere about the colder parts 
of the furnace and all the inner brick feels dry. The dryer the 
furnace is before it is filled the better it will work and the 
longer it will last. Any time or fuel that is expended in 
this way in drying it, is extremely economical in its results, 
both for the preservation of the brick work and the lengthening 
of the campaign, so that for this reason drying should be car¬ 
ried as far as possible, and any fuel so expended will be eco¬ 
nomically used, so that for this reason the filling should be de¬ 
ferred until the last moment or until the furnace is perfectly 
dry. When business is pressing the time occupied is sometimes 
as short as ten days, but two months is a better time, the longer 
the time the better. It is not intended nor expected that all 
the moisture should be expelled in this way. When the newly 
constructed furnace goes into blast it will often continue to give 
off steam in small quantities from the moisture of the lining for 
a month after it is blown in. The length of the campaign, 
other things being equal, will, however, generally depend on the 
way the furnace is first dried. 

While it is drying the tuyers should be put in, and all the 
water pipes should be tried to ascertain whether they are work¬ 
ing perfectly. The blast engine should be started and all the 
pipes and valves connected with it and the blast main should be 
examined to see that they are ready to work. The nozzle 
should be examined and placed in readiness to put up at once. 

When the furnace is ready the hearth is covered with sawdust, 
fine charcoal or anthracite dust to the depth of six inches at least. 
This is done to prevent any melted material which comes down 
after the furnace is fired, from sticking to the hearth. Sometimes 
no such precaution is taken, but the wood rests directly on the 
hearth. When the furnaces have a closed hearth a cribbing- is 
made with eight inch to ten inch blocks, from eighteen inches to 
two feet high, to support the wood above, which is filled in with 
light wood or shavings only, just enough being put in to light 
the wood. This light wood being relieved of any pressure ig¬ 
nites very easily. 

•f - 4t 

/t, r i U ' * ft' , 

- 1 


In the open breast furnaces a man gets into the hearth 
through the fore hearth, and fills it with sticks of cordwood from 
4 t° 4 % feet long, set on end, putting in generally only two 
tiers and filling the furnace to the height of eight to ten feet 
As soon as the furnace is so full that there is no longer room to 
work, the man comes out through the fore hearth and fills up 
all the remaining space that he can from the outside, putting in 
at the last dried shavings and small wood in the spaces not 
filled by the cord-wood, so that the furnace will light easily. 
When the hearth has a closed breast all the filling is done from 
the top. d he wood to be used should be hard and well seasoned, 
oak or hickory is preferred, but any other hard dry wood may 
be used. 

Long experience in the Lehigh district has shown that two 
tiers is about the best quantity of wood to be used. This is 
sufficient to light the furnace and any more than this may be 
injurious and likely to cause an accident. Occasionally the fur¬ 
nace is filled as high as 20 feet with wood, it being filled nearly 
to the boshes. There is always danger that an excess of wood 
above what is necessary to light the furnace will cause it to draw 
irregularly, the materials burning out at one side more than the 
other, and it may even cause an accident from excessive heat or 
produce a scaffold even before the blast is turned on. It is to 
be kept in mind always that when the wood burns out the stock 
must descend the whole height of the wood. If this took place 
suddenly it would cause a serious accident. It, however, takes 
place gradually, but much quicker than with the ordinary fuel, 
so that it must not be allowed to burn out too quickly, nor should 
there be too much of it. The time that it will take to put in 
the wood depends both on the quantity put in and the way it 
is introduced. If only two tiers are introduced from the fore 
hearth, as at Glendon, it will take about a day and a half. If it 
is lowered from the top it will take from six to twelve hours. 

When the wood is filled in below, and every part of the 
space which is left has been filled as tight as possible, the dam 
is put in position. The cover is now removed from the top of 
the furnace. As the wood will reach to the height of the top 
of the hearth or higher, pieces of boards are placed against the 
boshes in order to protect the bricks in that position against 
abrasion from the material that is to form the charge. This is 


4 


very desirable, and as there is plenty of old lumber about the 
furnace which is useless for any other purpose, it is a matter of 
no expense. If, however, there is none, new boards must be 
used, and for this purpose slabs will answer as well as anything 
else. They should be placed close together so as to be sure that 
no abrasion will take place before the bricks have received their 
proper glaze. As soon as the cover is removed from the top of 
the furnace a tackle is rigged for the purpose of letting the ma¬ 
terials down into the furnace. This is usually done in a bucket. 

On top of the wood ten to twenty, and occasionally as high 
as thirty, tons of coal, varying with the size of the crucible, are 
then piled. This should be freshly mined coal, as almost all 
coal deteriorates by being kept, and serious accidents have hap¬ 
pened to some furnaces owing to the fact that the coal they used 
in filling had been kept too long after mining. The coal is 
broken before being put into the furnace, to the size of six 
inches cube or steamboat size, and great care is taken to dis¬ 
tribute it as uniformly as possible over the top wood, no fine 
coal whatever being used. In some works it is simply shoveled 
in from the top. . This is a bad plan even for furnaces of less 
than sixty feet, and would be impossible in very large furnaces, 
since the height of the fall is so great as to break the coal and 
produce a great deal of fine dust, besides causing it to pack in 
the lower part. It is very undesirable, and may be dangerous. 

It is much better to let down all the coal in buckets and 
level it carefully by hand. In some of the furnaces the coal is 
charged in buckets until the furnace is half full, and the 
rest is shoveled in from the top. In so important a matter 
the time and labor which is saved by working in this way 
is of no account, since the expense attendant upon any accident 
would necessarily be very great, and it is much better and more 
certain to be successful to fill the furnace entirely with buckets. 
For the rest of the filling the practice is a little different in the 
different works although the principle is the same everywhere. 
At Glendon, five-eighths the weight of thecoalof carefully selected 
blast furnace cinder broken to the size of the fist is then put in. 
All the slag selected for this purpose should be very carefully 
chosen, that produced while gray iron is being made, being the 
best, and also slag which is very basic, as the substance that it 
is required to flux at this time is for the most part the ashes of the 





Section of Stock showing Filling. Filled Oct. 14th, 1880. Weight of Barrow, 

Cwt. Scale, 1 inch=i2 feet. 















































































































fuel, which are for the most part acid. At Glendon the charges 

# b 

used in the furnace are known as the single , which is used in 
the normal working of the furnace, and the double , which is used 
in the first stage of the filling. The double charge is composed 
of 24 barrows of coal, 12 barrows of slag, 6 of limestone, and 12 
of ore. The weight of the material per barrow is exactly the 
same for all kinds of material when filling. After four or five 
charges of this kind are made, two barrows of slag are replaced 
by two barrows of ore and one barrow of limestone, thus grad¬ 
ually substituting ore for cinder until it replaces it entirely, and 
the weight of the ore per charge is made equal to the weight of 
the coal. 

In this way the furnace is filled to the top, a few charges at 
the last being of the regular or single charge, 12 barrows of coal, 
6 of limestone, and 12 of ore. It is essential that these charges 
should be distributed as nearly as possible in horizontal layers, 
and that just as little fine material as possible should be used. 
This filling takes four to six days according to the size of the 
furnace. The annexed drawing for which I am indebted to 
Mr. F. Firmstone, shows the method of filling a No. 3 furnace 
at Glendon. At Bethlehem,* from 1 500 to 2000 pounds of cinder 
are charged on the coal and at every tenth succeeding charge un¬ 
til the furnace is filled. The cinder is withdrawn when near the 
top by first putting in a charge of coal and 2000 pounds of slag, 
and then going on with the regular charge of ore, coal and lime¬ 
stone. The filling takes sixty hours. At Port Henry, as shown 
by the annexed table,t 500 lbs. of slag are put in to 3000 lbs. of 
coal, which is gradually increased to 2000 lbs. and then, when 
the furnace is about half full, as gradually decreased until it is 
withdrawn. The charge of ore is increased regularly with every 
three to five charges, so that by the time the furnace is filled, 
the ore will weigh from 1 to 1 times the weight of the fuel. 
The amount of limestone is about five per cent. The time of 
filling is forty-eight hours, depending, however, on the way the 


* I am indebted to Mr. J. Fritz for details about the methods in use at 
Bethlehem. 

f I am indebted to Mr. F. Witherbee for this Journal of the filling of one of 
the Port Henry furnaces. 




6 


Journal of a Filling at Port Henry. 


Date. 

Charges. 

Common 

Limestone. 

Magnesian 

Limestone. 

Ore. 

Cinder. 

Coal. 



Lime. 

Magnesia. 




1878. 
Jan. 14 


IO 





lbs. 

15 


IO 





4000 



' 




5- 500 

3000 



20 

30 

60 


5-1000 

5-1500 


16 

- 

5 

90 

180 

600 

5-2000 

5-1000 




. 5 

112 

225 

750 

800 




5 

135 

276 

900 

600 


*7 


5 

157 

3i5 

1050 

400 

3000 



f 5 

180 

365 

1200 





5 

202 

405 

1350 



18 

- 

5 

225 

450 

1500 





5 

247 

495 

1650 





5 

270 

54° 

1800 





. 5 

292 

585 

1950 


3000 



5 

3*5 

630 

2100 





5 

337 

675 

2250 





5 

360 

P 

720 

2400 



*9 

- 

5 

382 

765 

2550 


3000 



5 

405 

810 

2700 





5 

427 

855 

to 

00 

Cn 

0 





5 

450 

900 

3000 





L 5 

472 

945 

3'5o 


• 

20 








(TO 

472 

945 

3*5° 



Total 

i«*_ 

5i7 

!°35 

34°° 


3000 

charges. 

131 






22 

34 

5*7 

io35 

3400 


» 

300 

2 3 

44 

517 

*035 

3400 


3000 

24 

4i 

5i7 

io 35 

3400 


3000 

2 5 

j 

TO 

5i7 

io 35 

3400 


3000 


1 

30 

54° 

1080 

3600 


3000 


Remarks. 


j Cords of wood to 
t top of bosh. 


Full to Flue. 

Put in bell. 
Fired at 11.20 P. M. 


Full after wood 
burned out. 


Put on wind at 2.35 
P. M. 

Gas under boiler at 
2.55 P. M. 

- Gas into stoves at 
No. 1, 3.25 ; No. 2, 
3.27 ; No. 3, 3.30. 
No explosions, cin¬ 
der 10.10 P. M. 

j Iron, 9 A. M., 17 
) tons. 

25^ tons. 


39K tons. 


On April 6th, the furnace 


came up to 5.000 lbs. of Ore to 3,360 lbs. of F uel. 
































7 


hoist is worked and its capacity. The furnaces both at Bethle¬ 
hem and Port Henry have closed breasts. 

The use of cinder was formerly unusual, but has grad¬ 
ually grown into favor, as the cinder above the first coal not 
only begins to melt almost as soon as the blast is put on, thence 
running down into the fore hearth and warming the bottom, 
fluxing the ashes of the wood and the coal, but it also helps to 
glaze the bricks of the furnace. The success in blowing in 
will depend very largely upon the bricks getting the proper 
glaze. The iron which is first reduced instead of becoming scat¬ 
tered, as in the method of scaffolding it must do, amongst the 
cold ashes below, sinks through the melted slag as in the fur¬ 
nace in regular work. This employment of cinder has always 
worked well, and its use is constantly extending. The cinder 
which flows at first, is much more vitreous than that which has 
been put into the furnace. Its color is sometimes dark brown, 
from a little iron or other impurities, but is never black. 
When no cinder is added limestone is put in with the first coal 
in order to flux its ashes. The quantity of lime required is a 
little less than that used in the regular working. The regular 
filling commences at this point, the charge being let down in 
the same way, and each charge containing twice as much coal 
as what is to be the regular charge in the furnace. It is dan¬ 
gerous to use much fine ore while filling the furnace, as it is more 
likely to sift down through the charge and to pack, than during 
the regular working. 

It is essential that sufficient space should be left between the 
parts of the charge to cause a good draft at the start. When 
the furnace is lighted the fire should come round regularly with¬ 
out any accident. There should be a good draft through the 
tuyers and under the tymp up into the furnace so that the fire 
will light regularly all around. A want of care in these respects 
will sometimes cause a great deal of difficulty. It is better 
generally to avoid the use of fine materials of any kind at this 
time. 

While the filling is going on, if it has not been previously 
done, every part of the outside of the furnace should be exam¬ 
ined to see that everything is in full working order, because it 
is desirable to light the furnace as soon as it is full. As this 
takes several days there is plenty of oportunity to examine 


8 


everything, for while a furnace may stand full of material for 
some time and blow in without any serious trouble, the charge 
is very apt to pack from standing, and serious accidents have 
occurred from allowing the furnace to be filled sometime before 
blowing in. Just as soon as the furnace is filled it should be 
lighted. This is done with shavings through the fore hearth 
which with all the openings at the bottom is left open, but the 
draft should be restricted so as to be certain that the wood does 
not burn too quickly. In the closed furnaces the lighting is 
done at the tap hole, cinder notch and tuyers at the same time, 
the ignition being often made with red hot iron bars put in through 
these openings. 

If the draft is good as it should be, at the end of six to ten 
hours the fire will generally appear at the tuyers next to the 
fore hearth, and pieces of ignited coal will begin to drop in front 
of the tymp. The fore hearth is now filled up with coal dust, 
which is covered over with a layer of loam and packed down 
with a shovel. Over this two heavy cast iron plates are put for 
weights to keep it in position. If the furnace has been properly 
filled there is generally a strong draft at the tuyers, and the fire 
will work around gradually and quickly. It however, some¬ 
times refuses to draw, when the weather becomes suddenly 
warmer than when the furnace was filled, because the materials 
inside are cooler than the outside air. If the draft is not good 
and the fire does not come round quickly, small nozzles may 
be put in and worked at a very low pressure by blowing in the 
open tuyer. 

There is always danger in allowing the fire to come round 
slowly by itself, for in this case the wood in the center of the 
furnace may be completely converted into charcoal, or be 
burned out before that at the outside has begun to take fire, and 
thus cause an irregular descent of the charge. It is therefore 
desirable to put the nozzle in to hasten the fire if it does not 
come around properly. After about ten hours more, or 16 to 
20 hours after the furnace has started, incandescent coal will be¬ 
gin to come down before the tuyers, which are closed at once 
with clay when,this takes place. 

As soon as the coal appears in front of the last tuyers, so 
that they have all been incandescent, they are all opened and 
the air is allowed to enter them in order to freshen up the fire 


9 


for about an hour before the blast is put on. The blast should 
be put on after no longer delay than this. At Glendon, the 
practice is to commence the blow gently as soon as all the wood 
is converted into charcoal. This is ascertained by thrusting a 
pointed iron rod through the tuyers. If there is no uncarbon¬ 
ized wood it can be pushed from wall to wall without difficulty. 
In some works the tuyers are not closed but the draft is ob¬ 
structed or the tuyer left open according as there appears to be 
a necessity for more or less draft. This is more especially the 
practice in furnaces with a closed breast. 

It will be possible if there is any accident, to bank the fur¬ 
nace at this time by stopping up all the tuyers and allowing it 
to remain so for 24 hours or even for twice that time, but there 
is always danger of scaffolds if at this stage any delay occurs in 
putting on the blast. There has been so much time to look after 
every part of the furnace and its machinery that there should be 
no accidents, as everything should not only be in perfect order 
but in good repair. The time from lighting to putting on the 
blast will be from 12 to 36 hours, depending somewhat on the 
weather but mostly on the filling. 

Before blowing, good fires should be lighted on the grates 
of all the boilers to insure plenty of steam, and a fire of wood 
should be started in the combustion chamber of the hot blast 
stoves if they are iron, or in the center of the brick stoves if they 
are regenerative. All of these fires should be started two or 
three hours before the blast is put on, so as to warm the walls 
and the pipes. There should always be a bed of incandescent 
coal under the boilers, and in the combustion chamber of the 
hot air stoves when the blast is put on, which renders certain 
the ignition of the gas as soon as it enters them, and prevents 
an explosion which would be likely to take place if the gas did 
not at once become ignited there. It is not best to put on the 
blast before the gas at the top is combustible. It is not how¬ 
ever best to light it before closing the bell, as explosions may 
occur in the space beneath the bell, or even in the interstices of 
the materials in the furnace. It is safest to commence with the 
charging bell open, and not close it until there is a good circula¬ 
tion of gas. The bell and all other outlets of gas are then closed 
almost tight and also all the valves leading from the gas flues 
to the stoves and boilers, thus driving all the air out ahead of the 


10 


gas through the small openings and leaks. By thus maintaining 
a good pressure in the flue an explosion is made impossible. 
When the air is out the valves must be opened very cautiously 
and one at a time. In some works the air is driven out by smoke 
from a smouldering fire made in the flues and combustion cham¬ 
bers and this is gradually replaced by gas. If a good fire has been 
kept up in the combustion chambers they will be well heated 
from the start, and no accident can take place. It is well always to 
maintain a plenum in the gas flues even when the furnace is in 
regular working. The bell should always be “ chocked” open 
from the time the furnace is lighted until the gas is let into the 
flues, as explosions are liable to occur in the furnace itself. From 
such explosions the bell and hopper have sometimes been lifted 
from theirseatsand the brick work around them shattered, or both 
the bell and hopper broken, a serious thing at such a time, as 
it occasions delay. In the open breast furnaces the stopping 
should be put in before the blast is started. The time of firing 
should always be so selected that the blast shall be put on and 
the gas ignited in the day time. 

About an hour after blowing is commenced the fore hearth 
is opened. If everything is in good working order, at this time 
the fine dust and the loam, with which the fore hearth is filled, is 
removed from it, and stopping under the tymp is put in. The 
fore hearth is again filled, and the weights which cover it are 
put on and propped down. 

In some of the furnaces a point is made of using smaller noz¬ 
zles to blow in with than are used during the regular working, 
the diameter in some cases being reduced to two inches. These 
are kept in from 12 to 24 hours according to the way in which 
the furnace is driven. They are after this time changed for 
those used in the regular working. In others, tuyers of the 
full size are used from the beginning. The space between the 
nozzle and the tuyer is carefully packed with clay, open tuyers 
never being used in anthracite furnaces. In the best practice 
seats are turned in the tuyers into which the turned end of the 
nozzle fits; this not only prevents leaks, but greatly facilitates 
changing the nozzles. 

After the blowing has commenced, fires should be started at 
once on top of the furnace and over the fore hearth, to ignite the 
gas as it escapes. If no accident has happened the material in 
the furnace will begin to sink regularly. As the charges descend 


new charges are added, keeping up the same charge as that 
which was last put into the furnace. The gas will generally come 
off in considerable quantities, but will not be very combustible 
at first, as it is cold and filled with steam, for which reason the 
fires must be carefully looked after. The gas is used from the 
start. It will be about 36 hours before it can be depended on to 
be used without fires. It will be possible to increase the tem¬ 
perature in the course of five or six hours to 6oo° or 8oo° F. 
The slag will rise and appear in front of the tuyers in three to 
twelve hours after the blowing has commenced, depending on 
the way the charge is made and the size of the crucible. What¬ 
ever cinder is melted before the blowing commences settles in the 
hearth and no attention is paid to it in the closed breast furnaces 
After the blowing the slag is allowed to accumulate and runs 
off through the cinder notch ; sometimes the first cinder is tapped 
through the iron notch to warm up that part of the furnace, but 
this is not always done. In the open breast furnaces the con¬ 
dition of the slag must be carefully watched in order to “spring 
the cinder” into the fore hearth. In many of the works they 
wait to do this until the slag appears in front of the tuyers. In 
others the cinder is sprung as soon as the flames under the tymp 
and over the fore hearth commence to diminish or disappear. 
This shows that the slag has risen so high as to prevent the 
escape of the gases at that point, and that there is sufficient of 
it to fill the fore hearth. This is a much safer way, as it avoids 
every possible difficulty with the tuyers. To spring the cinder 
some of the blast is taken off, only enough being kept on 
to prevent the cinder from entering the tuyers. The weights 
and covers are removed from the fore hearth which is cleaned 
and the slag admitted into it by driving heavy iron bars down 
obliquely under the tymp. This admits the slag to the fore 
hearth, heats it up and gets it ready for the iron. As soon as 
the fore hearth is full of slag the weights are put on again, and 
the regular pressure of the blast resumed. If from the first ap¬ 
pearance of the slag, or at any other time during the blowing 
in, there is any irregularity in its appearance the hearth is 
cleaned out. 

The iron will begin to appear in from 12 to 20 hours. If 
the hearth should become choked with cold slag or pieces of 
unconsumed coal, it may appear sooner, and may even run over 
the dam, if proper attention is not paid to it In a sixty ton 


12 


furnace if everything is working well, the first cast will be from 
14 to 15 tons, sometimes not more than 5 to 6 tons, but it is 
generally expected that it will be about one-third of the regular 
product. The normal working will usually not be arrived at in 
less than four or five weeks, but it is sometimes reached in two 
weeks. 

The quantity of blast should be increased very slowly. There 
are two ways of doing it. One is to blow at a low pressure, and 
increase the quantity by increasing the pressure, and the other 
to commence at once with the full pressure and to increase the 
size of the nozzles. The latter seems to be the most rational 
although it gives more trouble, as the nozzles have to be re¬ 
moved. If the number of tuyers is greater than three or four it is 
well to reserve some of them at first and blow say from only 
half of them, but with the full pressure, as it is easier to start a 
new tuyer than to change a nozzle. 

It is important to keep everything in the furnace moving 
regularly by properly handling the blast so as to prevent the 
danger of a hot scaffold, which is very apt to occur in blowing 
in if the blast is not properly handled. On no account should 
any attempt be made to force the furnace at first. It will not 
be economical so far as the length of the blast or of the cam¬ 
paign is concerned, to produce at once more than half or one 
third of what the furnace is expected to do in its normal work¬ 
ing. Ordinarily the furnace will not get to its normal condition 
in less than a month or six weeks after it starts. Every possi- 
sible precaution should be taken while the furnace is going into 
blast to avoid stoppages of any kind. It is impossible to tell 
what the effect of such stoppages will be, and every possible 
precaution should be taken to avoid them. 

Failures by this method are extremely rare and when they 
occur they are usually caused either from the unskilful filling in 
of the furnace, from allowing the furnace to stand too long be¬ 
fore it is fired, from the use of bad fuel, or too much fine ore, or 
from some delay. The most critical period is when the fur¬ 
nace is approaching its normal burden, which will generally 
be from two to three weeks after the blast is put on, for the 
maximum burden may or may not suit the conditions which 
are assumed for it, but by constant watchfulness with prompt 
action if needed, the furnace will generally work up to its proper 
condition without accident. 







































